1. Field of the Invention
The present invention relates to a transparent member used in an optical device having a chip as an optical element, an optical device using the transparent member, and a method of manufacturing the optical device.
2. Description of the Background Art
Referring to FIGS. 21 to 25, a first method of manufacturing a conventional optical device is described. Specifically, a method of manufacturing a package of a light-emitting diode (hereinafter referred to as an “LED”) is described as an example of a manufacturing method of the optical device. For the sake of simplicity, respective drawings in association with the description below are schematically depicted and not drawn to scale.
In the method of manufacturing the conventional optical device, as shown in FIG. 21, an LED chip 3 is first die-bonded to a top surface 2 of a lead frame 1 as a substrate. Then, electrodes (not shown) of lead frame 1 and LED chip 3 are wire-bonded to each other via a wire 4.
Then, as shown in FIG. 22, for example by transfer molding, a protecting member 6 composed of a cured resin is formed at a prescribed region on top surface 2 excluding the region around LED chip 3 and wire 4 and at a prescribed region of a bottom surface 5. Protecting member 6 serves to protect LED chip 3 and wire 4, and in some cases, to reflect light emitted from LED chip 3 in an upward direction of the drawing. Furthermore, when forming protecting member 6, a concave portion 7 is formed in protecting member 6 on the side of top surface 2. The process described above provides a partially-completed product 8 corresponding to an LED package as one completed product. In this partially-completed product 8, a portion protruding from protecting member 6 in lead frame 1 functions as a lead of the LED package. It is to be noted that, in the state shown in FIG. 22, secondary molding may be performed, as necessary, to fill the space around LED chip 3 and wire 4 with a cured resin having transparency.
As shown in FIG. 23, an adhesive (not shown) is then applied to concave portion 7 of partially-completed product 8, and a transparent member composed of a material having transparency, that is, a lens member 9 is prepared. Lens member 9 is thereafter transported in a state held by adsorption and the like, and aligned with concave portion 7 of partially-completed product 8. Lens member 9 individually manufactured by injection molding, includes a transparent portion 10 having a configuration of a partial sphere and functioning as a convex lens, and a plate-like flange portion 11 extending laterally at the bottom of transparent portion 10, and has a circular shape in plan view.
As shown in FIG. 24, lens member 9 is then lowered to be placed on concave portion 7, and the adhesive cures to bond lens member 9 and partially-completed product 8 shown in FIG. 22. Thus, a partially-completed product with a lens 12 shown in FIGS. 24 and 25 is completed. Subsequent to the above-described process, the lead is subjected to bending, whereby an LED package is completed.
In addition to the above-described manufacturing method, the following second manufacturing method is also known, depending on the structure of the LED package. In the proposed manufacturing method, a layered ceramic substrate is used instead of lead frame 1, and a metal cap is attached to the top surface of the layered ceramic substrate instead of protecting member 6, and a lens (a transparent member) is attached to a hole portion provided in the top surface of the metal cap. This manufacturing method is disclosed, for example, in Japanese Patent Laying-Open No. 2003-163382. The lens used in this method is a convex lens having a circular shape in plan view and a convex cross-section at its center portion.
In a manufacturing method proposed as a third manufacturing method, a light-emitting diode pellet (an LED chip) on a lead frame is sealed with resin to form a photoelectric conversion substrate having a rectangular shape in plan view, onto which a transparent resin plate (a transparent member) is mounted. The transparent resin plate has a plate-like portion which is rectangular in plan view and a convex lens portion integrated. This manufacturing method is disclosed, for example, in Japanese Patent Laying-Open No. 4-348088. The transparent resin plate with a lens is molded by an injection molding method.
However, the conventional method set forth above poses the following problems. First, in the first and second manufacturing methods, the lens (including the lens member in the first manufacturing method) has a circular shape in plan view and a convex cross-section at the center portion. This makes it difficult to pick up the lens by gripping or adsorption and the like and to handle the lens during transportation even if the lens has a small area of a flange portion. In addition, if a jig for a handling operation contacts a portion through which light of the lens passes (transparent portion 10 in FIG. 25), the lens will be damaged. Also, management of inventory and processes become complicated because it is necessary to store, pick up and transport individual lenses in all of the first to third manufacturing methods. Furthermore, it is difficult to improve the efficiency of manufacturing LEDs because it is necessary to manufacture lenses and partially-completed products one by one and then attach one lens to one partially-completed product in all of the first to third manufacturing methods.